In light of the flowering of all manner of religious and spiritual practices it would seem that the secular project has run into the mud. This essay asks why this has happened by means of three major points: a reconsideration of the definition of secularism and its derivatives; and exploration of their paradoxes; an extended exploration of the separation of church and state. I begin with the definition of secularism: it is a way of thinking and living that draws its terms, beliefs and practices from this age and this world (Latin saeculum and saecularis). If we take this definition then the other senses of secularism become secondary or derivative: the anti-religious nature of secularism; the separation of church and state; the distinction between scientific academic study and theology; the separation of civil and ecclesiastical law. However, a close look at each derivative reveals some deep contradictions, especially with regard to the separation of church and state. The discussion turns to an old discussion that is increasingly relevant, namely the deliberations of Marx and Engels concerning the emergence of the secular state as an attempted resolution to the contradictions of the Christian state. The next step is to explore the implications of this discussion in relation to the USA, Turkey and Australia. Finally, the article asks what is to be done. If you call your state a general Christian state, you are admitting with a diplomatic turn of phrase that it is un-Christian (Marx 1975 [1843]-b: 118; 1975 [1843]-a: 106). The precarious separation of church and state is, once again, under threat. From the invocation of a vague ‘Christian heritage’ by European countries, through the contradictory debates over (Muslim) head-coverings in France and Denmark, to the open avowals of Christian belief and its effect on their political lives by leaders in the UK, Australia and Malaysia, it has once again become clear that the separation of church and state is either an impossible goal or a political fiction. At the same time, a number of major studies have appeared that challenge assumptions concerning secularism. For example, Charles Taylor argues that secularism entails not the banishment of religion but other, diverse ways of being religion. And Talal Asad proposes that the separation of religion and the state is not the removal of religion from public affairs but another means for the state to control religion. These developments raise once again the old-become-new question of the separation of church and state. Is it not crucial to maintain a separation of church and state, or religion and politics? However, the deeper issue is secularism itself, which needs to be addressed before any discussion of church and state may take place. So in the following discussion I return to some basics, outlining the definition of secularism and its secondary developments. From there I focus on the question of the separation of church and state, exploring its paradoxes through some surprisingly relevant material from Marx and Engels and then some observations on the USA, Turkey and Australia. Finally, I ask what the implications might be for politics.